1. Field of the Invention
The present invention relates generally to electronic component inspection apparatus, and more particularly to a device for verifying that the leads on surface mounted electronic components are complanar within established limits.
2. Description of the Prior Art
With the advent of integrated circuit packages having contact legs extending downwardly and either flared outwardly or rolled beneath the package, so that the device can be surface mounted to a printed circuit board by merely soltering the leads to the board contact pads, it became necessary to determine that the contact points of all of the leads were coplanar within established limits, so as to ensure that proper electrical contact was made between the circuit board and all of the leads of the device Packages of the above-referenced to type are variously referred to as plastic leaded chip carriers (PLCC's), small outline IC (SOIC) carriers, gullwing packages J-lead packages, etc.
These devices can be manually inspected by placing the device on a smooth surface and noting any separation between the contact points of any lead and the smooth surface. The devices can also be visually inspected by sighting down the row of contact pins and noting excessive variation. These types of inspection are of course not highly reliable because of the tolerances involved.
Machines have also been developed which perform an automatic optical inspection of the coplanarity of the package leads. However, such machines are typically quite expensive and inconvenient to use at the point of board installation.